JPS6311994A - Lighting controller for multi-color display panel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a lighting control device for a multicolor display panel used to display the times and destinations of arriving and departing trains, etc. at railway stations, etc. Specifically, a multi-color display panel is provided in which one pixel is constituted by a set of a plurality of light emitting diodes that each emit light of a different color, and each of the light emitting diodes in the set is turned on based on instruction information of the display color. The present invention relates to a lighting control device for a multicolor display panel, which is provided with lighting control means that changes the display color displayed by the set of light emitting diodes by controlling the above.

[Conventional technology]

The lighting control device for this type of multicolor display panel described above controls the lighting of the monochrome light emitting diodes that emit a plurality of different colors that make up each pixel. By mixing them, it is possible to display display information in a color different from the display color of the monochromatic light emitting diode itself that constitutes each pixel. For example, depending on the importance of the displayed information, ,
By changing the display color, much of the information displayed on the display panel is made easier to see.

By the way, if the lighting control device is constructed using a static method that controls the lighting of all the light emitting diodes individually, the number of circuit components such as switching transistors that drive each light emitting diode will be equal to the number of pixels that make up the display panel. Conventionally, the so-called dynamic scanning method has been used to control the lighting of the light-emitting diodes that make up the pixels of the display panel. 1 [I try to do 1. For example, one pixel is constructed using two monochromatic light emitting diodes, red and green, and by lighting up these monochromatic light emitting diodes simultaneously, the emitted light colors are mixed, and the displayed color on the display panel is changed to red, green, red, etc. green, and
A method to change the color to orange is being considered.

To explain the above conventional means, as shown in FIG. 4, a light emitting diode element (D ),
They are arranged in a matrix to form a multicolor display panel (1), and light emitting diodes (
The anodes of the red light emitting diodes (Dll) and the green light emitting diodes (DG) of D) are commonly connected, respectively, and the cathodes of the red light emitting diodes (DR) and the green light emitting diodes (DG) are - A common connection is made for each row. Then, the anodes of the red light emitting diodes (0, +) commonly connected in the column direction are used for red color, into which red display data (si) as display color instruction information indicating whether red is lit for each pixel is input. shift register (
2R) is driven by the output of the red light emitting diode (
Da) 0N10FF energization in the column direction for each column P
The anodes of green light emitting diodes (DG) driven by an NP type driver (3R) and commonly connected in the column direction display green as display color instruction information indicating whether each pixel is illuminated with green. A PNP type driver (3G) that is driven by the output of a green shift register (2G) into which display data (SC) is input and energizes the green light emitting diodes (DG) in the column direction to 0N10FF for each column. The cathodes of the red light emitting diodes (DR) and green light emitting diodes (D,) commonly connected in the row direction are driven by the row scan clock (Cp).
The information displayed on the display panel (1) is configured to be driven by an NPN type driver (5) connected to a scanning counter (4) that repeatedly scans in the row direction. The red light emitting diode (D,) that constitutes
and a lighting control means (A) capable of scrolling the display information in the row direction while changing the display color based on the display color instruction information while lighting the green light emitting diodes (DG) in a time-division manner. there were.

As shown in FIG. 5, each of the shift registers (2R) and (2G) of the above-mentioned 2 & Il has a red and green as a set, and sequentially input display data for each pixel, and the PNP type driver (3R) at the intersection of each row and each column,
Only when the (3G) and NPN type driver (5) are turned on at the same time, the red light emitting diode (
The color displayed on the display panel (1) is controlled so that [lR) and the green light emitting diode (DG) are lit.
The color can be changed to three colors: red, green, and orange.

In other words, if the display color of each pixel is to be red, the display data (SC
) to “1” and shift register for green color (2G)
The display data (S6) to be input to is set to "O", and if the color is to be green, the shift register for green color (
The display data (SC) input to 2G) is set to "1", and the display data (sg) input to the red shift register (2R) is set to 0''.Then, the display color is set to orange. , the red and green display data (s+i) and (sG) input to both shift registers (2R) and (2G) at that display pixel position are both “
It was configured to turn on red and green at the same time by turning the light on to 1".

[Problem that the invention seeks to solve]

By the way, the maximum luminance obtained by a light emitting diode depends on the value of the current flowing through it, so in order to increase the brightness of the display panel, it is sufficient to increase the value of the current flowing through the light emitting diode. Furthermore, since semiconductor elements such as the above-mentioned light emitting diodes need to be used below their maximum allowable dissipation, the current value that can be energized is limited when considering the temperature rise of the element due to energization.

Also, when using a light emitting diode element (D) in which the red light emitting diode (DR) and the green light emitting diode (DG) are sealed in one package as a set,
It must be used at a current value that is less than the maximum allowable loss for each light emitting diode element (D), and it is necessary to ensure that the total loss of the two colors is less than the maximum allowable loss.

Therefore, as in the above conventional configuration, red light emitting diodes (D
In a configuration where the display color is orange by simultaneously lighting up the green light emitting diode (DG) and the green light emitting diode (DG), it is necessary to make the loss per color light emitting diode half or less of the total of the two colors. Therefore, when lighting either a red light emitting diode (DR) or a green light emitting diode (DG) to make the display color red or green, it is compared to lighting both colors simultaneously to make the display color orange. As a result, the current flowing per pixel is low, resulting in low brightness.As a result, when a display panel is configured to display multiple colors, there is a disadvantage that the entire display panel cannot be made to have high brightness. be.

Therefore, in order to make the display brightness of each color the same, it is considered that when red and green are turned on at the same time, the current flowing through each light emitting diode is halved compared to when they are turned on individually. However, in that case, it is necessary to separately provide means for switching the energizing current, which has the disadvantage of complicating the device configuration.

The present invention has been made in view of the above circumstances, and its purpose is to control the lighting of a plurality of light emitting diodes of different colors to variably display a plurality of colors on a display panel. The purpose is to enable each display color to be displayed with maximum brightness.

[Means for solving problems]

A characteristic configuration of the lighting control device for a multicolor display panel according to the present invention is such that the lighting control means is configured to cause the display color instruction information to cause the set of light emitting diodes to light simultaneously (if instructed, The light emitting diodes of the present invention are configured to be turned on alternately, and the functions and effects thereof are as follows.

[For production]

In other words, if a set of light emitting diodes that make up each pixel on the display panel are instructed to turn on at the same time, the maximum allowable loss per pixel can be exceeded by turning on the light emitting diodes alternately. The display color is a mixture of the emitted light colors of a plurality of light emitting diodes, while ensuring that there is no color difference.

〔Effect of the invention〕

Therefore, since the plurality of light emitting diodes that make up each pixel of the display panel are turned on alternately to mix the emitted light colors,
A plurality of light emitting diodes do not light up at the same time as in the past, and the loss per pixel becomes independent of the display color.

In other words, the loss per pixel does not change even if the display color is changed, so whether you turn on one light emitting diode to display a single color or mix the display colors of multiple light emitting diodes, the loss per pixel remains the same. The maximum allowable loss of
Maximum brightness can be obtained even when displaying a single color. As a result, it has become possible to provide a display panel with high brightness regardless of the displayed color.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

As shown in Figure 1, a set of red light emitting diodes (D,
) and a green light emitting diode (D.) are arranged in a 7-trix pattern, and the display color can be changed to three types: red, green, and orange. A multicolor display panel (1) is formed.

The red light emitting diodes (D
8) and the anodes of the green light emitting diodes (D,) are commonly connected for each color, and the cathodes of the red light emitting diodes (DI) and the green light emitting diodes (DG) located in the same row are commonly connected. It has been done. Then, the commonly connected anodes are connected to red and green respectively.
A pair of PNP type column drivers (3R) that are sequentially and repeatedly scanned by one column scanning counter (4),
(3G), and the commonly connected cathodes are connected to an NPN type row driver (5) that sequentially and repeatedly scans the lighting of each row in synchronization with a row scan clock (CPU). .

Further, the row driver (5) is connected to one shift register (2) for scrolling display data (So) in the column direction for instructing whether or not to turn on each pixel, and the By scanning the row scan clock (Cr') and the column scan clock (CPz) for the column scanning counter (l[),
- Lighting control that allows each of the red light emitting diodes (D,) and green light emitting diodes (DG) to be lit in a time-division manner for each pixel, and to freely scroll displayed information in the column direction, that is, in the vertical direction of the display panel (1). This constitutes means (A).

However, the column scan clock (CP) manually input to the column scanning counter (4) is synchronized with the row scan crofter (CPI), and the column scan clock (CP) is scanned at twice the frequency of the column scan clock (Cr'). Black ivy (cp,
) is divided by 2 by a frequency divider (6) and inputted, and the pair of PNP type column drivers (3R
), (3G), which outputs a set of control signals (QR), (QG) for individually controlling the operation of 0N10FF in synchronization with the column scan clock (CPz).
A type of flip-flop (7) is provided in the flip-flop (7), and a set of colors as display color instruction information for changing the display color input to each input terminal of the flip-flop (7). The pair of P N P is synchronized with the scan clock (CPO) having twice the frequency of the column scan clock (cpz) using the control signals (sR) and (SG).
The operation of the type column drivers (3R) and (3G) is individually controlled by 0N10FF.

In other words, as shown in FIG.
A pair of color control signals (SR), (S
By changing the combination of states (“1” or “0”) of G), the pair of column drivers (3R), (3
A control signal (QR
), (QG) is the column scan plotter (CPU)
is output in synchronization with the column scan clock (CPZ
) during the scanning period (1) in which one pixel of
The red light emitting diode (DR) and the green light emitting diode (Dc) are turned on alternately, and the shift register (2
) The display color of the pixel that is turned on is configured to be variable to red, green, and orange based on the display data (So) input to the display.

The table below is a truth table showing the relationship between the states of the pair of color control signals (SR) and (Sc) input to the flip-flop (7) and the displayed color.

Therefore, the display data (So) for each pixel input to the shift register (2) and the flip-flop (7)
), a pair of color control signals (st+), (S
G) in synchronization with the row scan clock (CP, ) and column scan clock (cpz),
It is possible to switch between the three colors of red, green, and orange while keeping the luminance of each color the same. In addition, if only the color of the entire information displayed on the display panel (1) is to be changed, the combination of the pair of color control signals (si) and (SG) input to the free knob flop (7) can be displayed. There is no need to change it in synchronization with the input of the data (So), and it can be set independently of the display data (So) based on the above table.

Also, even if you change the display color, the red light emitting diode (D, l)
Since the red light emitting diode (DR) and the green light emitting diode (D6) do not light up at the same time, the shift 1 register (2) and scanning counter (4) that control the lighting of each pixel are replaced by the red light emitting diode (DR) and the green light emitting diode (D6). Dyed (D6)
The device configuration can be simplified.

In addition, even if the display color is changed, the red light emitting diode (DR) and green light emitting diode (DG) will not light up at the same time, so the loss per pixel will be the same even if the display color is changed, and the loss per pixel will be the same. The current applied per pixel can be set to the maximum brightness within the allowable loss of one monochromatic light-emitting device constituting one pixel. As a result, the brightness of the display panel (1) can be maximized within the allowable dissipation of a single monochromatic light emitting diode, making it possible to construct a high-brightness display panel (1) and making heat dissipation and wiring easier to handle. It is possible to reduce the price.

In particular, in the above embodiment, when the display color is green, which tends to have poor visibility, the brightness can be increased, which greatly improves the visibility, and the display performance of the display panel (1) is greatly improved. It was done.

[Another example]

In the above embodiment, the lighting side i1 [1 means (A) is configured by alternately switching a red light emitting diode (DA) and a green light emitting diode (DG) during a scanning period (L) in which one pixel is scanned. In order to turn on the light, a pair of column drivers (2R),
(2G) operation, scan clock (CP, ),
(CPU), but for example, the column drivers (2R), (2G
) and the row driver (5) may alternately scan the entire range of red light emitting diodes (DR) and green light emitting diodes (DG) to vary the emitted light color.

That is, as shown in FIG. 3, the column scan crofter (cp,
), and the scan clock (CP, ) with twice the frequency
and the color control input to the flip-flop (7) in synchronization with a synchronization signal (S,) output every time the column scanning counter (4) scans once. Signals (SR) and (SG) are the column driver (2R).

(2G) and display panel (1G).
), red is displayed in the odd-numbered scans, and green is displayed in the even-numbered scans. may be displayed.

Furthermore, in the above embodiment, the display data is configured to be scrollable only in the vertical direction, but the column driver (
2R), (2G) and the row driver (5), it is also possible to scroll in the row direction. Furthermore, shift registers may be provided in each row and column so that the drive data of the row and column drivers can be scrolled in both the row and column directions. Furthermore, instead of scrolling the display data using a shift register, the input display data and color control signal may be changed in advance according to the scroll direction and then input. The specific configuration of can be changed in various ways.

Further, in the above embodiment, the duty ratio of the lighting time of two light emitting diodes that emit red and green light is 50.
%, but by changing the lighting time ratio of each color's light emitting diodes within the scanning time (1) in which the light emitting diodes of one pixel are lit, the orange color is displayed. Furthermore, a large number of colors can be displayed. Furthermore, by adding a different color, for example, a blue light emitting diode, and alternately lighting up the three different colors of light emitting diodes and varying the lighting time ratio of the three colors, the mixing ratio of each color can be changed. It may also be configured to display a larger number of colors. Even when the light emitting diodes of three colors are turned on alternately, it is possible to prevent the light emitting diodes of a plurality of colors from being turned on at the same time, as in the above embodiment. In other words, the specific configuration for alternately lighting up a plurality of light emitting diodes of different colors can be modified in various ways, and the present invention is not limited to the above embodiments.

[Brief explanation of drawings]

1 to 3 show an embodiment of a lighting control device for a multicolor display panel according to the present invention, FIG. 1 is a block diagram showing the configuration of the control device, and FIG. 2 is a time chart showing its operation.
FIG. 3 is a block diagram showing the configuration of another embodiment. Fourth
The figure is a block diagram showing the configuration of a conventional example, and FIG. 5 is a time chart showing its operation. (1) Display panel, (DG), (DG)
...Light emitting diode, (SR), (SJ...
. . . Display color instruction information, (A) . . . Lighting control means.

Claims (1)

[Claims] A plurality of light emitting diodes (D_
A multi-color display panel (1) in which one pixel is composed of a set of R) and (D_G) is provided, and display color instruction information (S_R) is provided.
, (S_G), the set of light emitting diodes (D
By controlling the lighting of each of _R) and (D_G),
A lighting control device for a multicolor display panel, comprising a lighting control means (A) for changing display colors displayed by the pair of light emitting diodes (D_R) and (D_G), wherein the lighting control means (A) ), the display color instruction information (S_R), (S
_G) is the set of light emitting diodes (D_R), (D_
A lighting control device for a multicolor display panel, wherein the lighting control device for a multicolor display panel is configured to alternately light up the set of light emitting diodes (D_R) and (D_G) when an instruction is given to light up the light emitting diodes (D_R) and (D_G) at the same time.